This invention relates generally to bag discharge systems and more particularly to a new and novel bulk bag discharge unit having a novel hopper designed to retain the inner liner of a bulk bag during discharge.
It is known in the various industries to use large bulk bags for moving products such as pharmaceuticals, food products, toxic products, aspirin, chlorine pellets and others within a given industrial plant. The large bulk bags can weigh between 750 pounds and up to 4000 pounds and generally have an inner throwaway liner contained inside the bag. By referring to FIGS. 1-4 of the drawings there is shown generally by the numeral 10 a typical bulk bag of the type before mentioned. A plurality of lifting loops 12 are used to lift the bag 10 by using a forklift truck. A typical bag 10 may be constructed of woven polypropylene and would have an outer diameter of 42 inches with an 18 inch diameter upper filling spout 14. A tying cord 16 is used to tie the bag shut after it is filled.
The bulk bag 10 also has a lower emptying spout 18 which may be 14 inches in diameter and is tied shut by a tying cord 20. FIG. 2 shows a bottom plan view of the bag as it would appear after being filled with the tying cord tied shut and with the inner liner 22 tucked inside the bag 10 prior to being tied. A top plan view of the bag 10 would also look similar to FIG. 2 after the bag was filled with a bulk product 21. FIG. 3 shows a cross-sectional view of the bulk bag 10, taken along line 3--3 of FIG. 1 and shows how the liner 22 is positioned inside the outer bag 10.
The bag 10 may be 24-80 inches long and the inside liner 22 would be formed of a 44 inch diameter polypropylene tube in a typical size with the liner usually being 2-6 mil thick. FIG. 3 shows a bag 10 with the inner liner 22 opened as the bag may appear when it is being emptied. The inner liner 22 may extend out of the bag about 18 inches prior to its being emptied as shown by the arrow direction 23. The liner 22 also has an upper liner filling spout 24, shown in FIG. 1, as well as a lower liner discharge spout 26. Tying cords 25 are used to tie the upper liner filling spout shut after the bag has been filled and tying cords 27 are used to tie the lower discharge spout shut prior to the bag being filled. When the bag 10 is to be emptied, the bulk product 21 will empty out, in the direction of the arrow 28, of the liner into a hopper where it will be conveyed to an in-plant system by means of an auger or a pneumatic conveying system.
Referring to FIG. 4 there is shown a cross-sectional view similar to FIG. 3 showing the bag 10 being emptied and how the inner liner 22 extends out of the lower bag discharge spout 18. As the bulk product 21 flows out of the liner 22 it tends to pull the liner out of the bag as shown in FIG. 4. The liner 22 can extend out of the bag, as shown by the arrow 29, by as much as 6 feet which can cause problems in the hopper usually positioned beneath the bag 10.
The excess liner 22 which is pulled out of the bag 10, by the amount shown as the arrow 29 in FIG. 4, can interfere with the operation of the lower conveyor system or auger. In addition a discharge valve may also be used at the bottom of the hopper and the excess liner 22 can interfere with the operation of the valve.
Prior to the advent of the applicant's novel invention, in order to overcome the problem of the excess liner 22, shown in FIG. 4, interfering with the lower devices below a hopper, the bulk bag 10 was lifted by a forklift truck or hoist upwardly as the bag was emptied to compensate for the excess liner 22 extending out the bottom of the bag 10. The solution would require excessively high ceiling heights in the plant to raise the bag upwardly so that the excess liner 22 would not get into the conveyor or valve.
Since the bulk bags 10 were introduced approximately 12 years go in the United States, the inner liner 22 usage began about 6 years ago and appears likely to continue. The use of the inner liner 22 allows a multiple use of the bag 10 and permits a cleaner product with no moisture or varment contamination. As a result, the problem of what to do with the excess liner extending out of the bag 10 as it is being emptied has remained until recently solved by the applicant's new and novel device.